Oil production could be increased by using optimization techniques in each stage of oil production system from field to production unit. However, the maximum profit will be obtained once integrated optimization of surface and subsurface components of the oil production system is implemented. In addition, when using high-tech equipment and facilities, an integrated study of well and surface facilities affects the economic benefits significantly. In this work, one of the Iranian brown fields (mature or declining production fields) was studied to find the best renovation plan with maximum profits. The base scenario was designed with four stages of separation, and the high-pressure gases from the first and the second separator were planned to be sold, while the low-pressure gases from subsequent stages were supposed to be flared. In this paper, two additional scenarios, namely separator optimization and full optimization, were proposed and 12 cases were defined. In the full optimization scenario, low-pressure gases were prevented from being flared. It was observed that by stopping the flaring systems, gas production rate increases as high as 20% and 150 to 200 MW power will be generated in all cases during the next 20 years. Finally, economic evaluation for all of the cases was done and different cases were compared in terms of incremental annual worth and payback period.